1. Field of the Invention
This invention relates to alternating pressure ads, and in particular to alternating pressure pads of the kind used in the prevention and management of decubitous ulcers in bedridden patients.
2. Discussion of the Related Art
The formation of decubitous ulcers, commonly known as bed sores, results from, amongst other things, the pressure applied to certain portions of the skin of a bedridden patient. It is known to meet the requirement for the prevention and management of decubitous ulcers with an alternating pressure pad comprising two series of alternatively inflatable cells which are interleaved, one series within the other. The cells are alternately inflatable to support a patient at different locations. Typically, inflation and deflation cycles may last from under two minutes for a gentle massaging effect to over twenty minutes.
Patient comfort dictates that support provided by a given region of a pad is not affected by the pressure applied by a patient to adjacent regions. Therefore, a pad of small cells is more comfortable to the patient than a pad of large cells, and a pad comprising small cells in a zig-zag or T-shape or similar path across the pad provides optimum comfort.
However, these small cell pads are unable to support the heavier patients or the larger bony protuberances of even relatively light patients unless pressurised to an uncomfortably high support pressure.
Consequently, in order to provide sufficient support it has been found necessary to use pads with large cells which inflate to a greater thickness and at a lower, more comfortable pressure. Typically, large cells have been used in the form of an elongate cylinder extending linearly straight across a pad. However, these pads have experienced problems of large areas of the body being left unsupported, or the areas supported feeling uncomfortable leading to patient discomfort and uneasiness. The cells have also been unable to prevent bony protuberances falling between the inflated cells and resting on the mattress beneath, or bottoming of the patient in the semi-recumbant position where the cells are prone to separate out under the patient's sacrum.
Reconciling the advantages of small cells to large cells has hitherto been accomplished by providing double layer small cell pads or smaller diameter cells under the heels of the patient.